1. Field of the Invention
The present invention relates to an electronic package.
2. Description of Related Art
Present electronic packages typically contain an integrated circuit (IC) that is mounted to a ceramic substrate. The IC is encapsulated by a lid that is hermetically sealed to the substrate. Because of the tolerances in the individual components, the packages must be designed so that there exist a gap between the lid and the integrated circuit. To improve the thermal efficiency of the package, a thermal grease is typically inserted between the IC and the lid. The thermal grease provides a conductive path between the electrical device and the lid.
The application of thermal grease requires several process steps and must be contained while the lid is attached to the substrate. A misapplication of the thermal grease may cause some of the grease to flow in between the integrated circuit and the substrate. The existence of grease between these two members may degrade the performance of the chip.
Thermal grease also has a low temperature tolerance, such that only low temperature adhesives can be used to attach the lid to the substrate. It has been found that low temperature adhesives do not always provide a complete hermetical seal for the package. Additionally, thermal grease is a relatively poor thermal conductor, such that the package may produce unacceptable junction temperatures in the integrated circuit. It would therefore be desirable to have an electronic package that is thermally efficient and does not require thermal grease.